If its anything like the MTW demo then you can mod it a lot, and I'm sure it is. Take a look at the files for the Trebia battle for example. You can add and subtract units as you want to (at least I'm sure you can, I don't have the demo yet if anyone wants to share ). So you can pretty much make a new scenario however you want to.

And I have to work all day tomorrow, then my cruel girlfriend is making me come visit her till Tuesday....so if anyone wants to share with me I'd be grateful.